Three frequencies make the band-gap threshold visible. Exact arithmetic here means exact results for the stated model inputs; measured inputs still carry uncertainty and significant-figure limits.
highlighted = computed this step
Below-gap frequency rejects absorption
With h equal to 2 joules per hertz, frequency 2 hertz gives photon energy 4 joules. The accepted bit is 0 and excess is 0 joules.
E=hf=2⋅2=4J<Eg=6J,accepted=0
Threshold frequency is the equality row
With h equal to 2 joules per hertz, frequency 3 hertz gives photon energy 6 joules. The accepted bit is 1 and excess is 0 joules.
E=hf=2⋅3=6J=Eg=6J,accepted=1
Above-gap frequency accepts and leaves excess
With h equal to 2 joules per hertz, frequency 4 hertz gives photon energy 8 joules. The accepted bit is 1 and excess is 2 joules.